DEVELOPMENT OF WAFER LEVEL PACKAGE (WLP) OF NORMAL AND HIGH PIN COUNT DEVICES FOR MOBILE APPLICATIONS

摘要

To apply WLP to various devices from small pin count to high pin count devices, various types of WLP have been developed and evaluated in terms of package size, structure and materials. Firstly for the application of small pin count, the reliability for Wafer Level Package of 6×6 ball array (36 balls) in 0.5mm pitch had been evaluated over TC (Temperature Cycling) and HTS (High Temperature Storage) at package level and passed. Then, the reliability for WLP of 9×9 ball array (65 balls, depopulated array) in 0.4mm pitch has been evaluated by employing TC, THT (Temperature Humidity Test), 4-point bending and Drop test at board level. All test items have been passed. To verify the application of high pin count devices, Wafer Level Packages of solder ball array 12×12 (144 balls) and 14×14 (196 balls) in 0.4mm pitch have been fabricated and tested over various reliability tests. Package level reliability tests for precondition level 3, multi-reflow, PCT, HTS and TC have been evaluated and passed. Board level reliability has been proven through various reliability tests. For one package for both small and high pin devices, Wafer Level System in Package(WLSiP) which has two chips inside one WLP has been developed. To optimize the structure and materials for WLSiP, various reliability tests had been performed in terms of die size and material type. According to the above results, WLSiP test vehicle has been designed and fabricated to evaluate the package level and board level reliability tests.